U.S. patent number 8,678,779 [Application Number 12/718,395] was granted by the patent office on 2014-03-25 for fuel pump.
This patent grant is currently assigned to Hitachi, Ltd.. The grantee listed for this patent is Harsha Badarinarayan, Akira Inoue, Donald J. McCune, Takashi Yoshizawa. Invention is credited to Harsha Badarinarayan, Akira Inoue, Donald J. McCune, Takashi Yoshizawa.
United States Patent |
8,678,779 |
Yoshizawa , et al. |
March 25, 2014 |
Fuel pump
Abstract
A high pressure fuel pump for use with a direct injection engine
having a housing which defines a pump chamber. A port is formed in
the housing which fluidly connects a fuel in the passageway with
the pump chamber. An elongated valve is movably mounted within the
housing between an open and a closed position. In its open
position, the inlet passageway is fluidly connected with the pump
chamber while, conversely, in the closed position the fuel valve
blocks the fluid flow between the inlet passageway and the pump
chamber. A circuit controls the deceleration of the valve to reduce
pump noise.
Inventors: |
Yoshizawa; Takashi (Novi,
MI), McCune; Donald J. (Farmington Hills, MI),
Badarinarayan; Harsha (Canton, MI), Inoue; Akira
(Farmington Hills, MI) |
Applicant: |
Name |
City |
State |
Country |
Type |
Yoshizawa; Takashi
McCune; Donald J.
Badarinarayan; Harsha
Inoue; Akira |
Novi
Farmington Hills
Canton
Farmington Hills |
MI
MI
MI
MI |
US
US
US
US |
|
|
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
|
Family
ID: |
44121503 |
Appl.
No.: |
12/718,395 |
Filed: |
March 5, 2010 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20110217186 A1 |
Sep 8, 2011 |
|
Current U.S.
Class: |
417/297;
251/48 |
Current CPC
Class: |
F02M
59/367 (20130101); F02M 59/44 (20130101); F02D
41/3082 (20130101); F02D 41/3845 (20130101); F02D
41/20 (20130101); F02M 59/366 (20130101); F02M
63/0038 (20130101); F02D 2041/2027 (20130101); F02M
2200/315 (20130101); F02M 2200/9084 (20130101); F02M
2200/304 (20130101); F02D 2041/2037 (20130101); F02M
2200/302 (20130101); F02M 2200/26 (20130101) |
Current International
Class: |
F04B
49/22 (20060101) |
Field of
Search: |
;251/48
;417/297,298 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2003-007531 |
|
Jan 2003 |
|
JP |
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2003-161226 |
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Jun 2003 |
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JP |
|
Other References
Japanese Office Action dated Mar. 21, 2012 relating to JP
Application No. JP 2010-209011. cited by applicant.
|
Primary Examiner: Freay; Charles
Assistant Examiner: Stimpert; Philip
Attorney, Agent or Firm: Gifford, Krass, Sprinkle, Anderson
& Citkowski, P.C.
Claims
We claim:
1. A fuel pump comprising: a housing defining a pump chamber, a
port formed in said housing which fluidly connects a fuel inlet
passageway to said pump chamber, an elongated valve axially
slidably mounted in said housing and having a valve head, said
valve movable between an open position in which said valve head is
spaced from said port thus allowing fluid flow through said port,
and a fully closed position in which said valve head contacts said
housing around said port and prevents fluid flow through said port,
a solenoid which controls the movement of said valve, an electrical
control circuit electrically connected to said solenoid which
generates a continuously decreasing output current to control the
solenoid for continuously decelerating said valve as said valve
moves from said open to said fully closed position.
2. The fuel pump as defined in claim 1 wherein said electrical
control circuit generates a pulse width modulated output signal to
said solenoid.
3. The fuel pump as defined in claim 2 wherein said electrical
control circuit varies the width of the pulses as said valve moves
from said open to said closed position to decelerate said valve
prior to contact between said valve head and said housing.
4. A fuel pump comprising: a housing defining a pump chamber, a
port formed in said housing which fluidly connects a fuel inlet
passageway to said pump chamber, an elongated valve axially
slidably mounted in said housing and having a valve head, said
valve movable between an open position in which said valve head is
spaced from said port thus allowing fluid flow through said port,
and a fully closed position in which said valve head contacts said
housing around said port and prevents fluid flow through said port,
said housing having a magneto-rheological fluid (MRF) chamber
surrounding at least a portion of said valve, an MRF coil contained
in said housing around said MRF chamber, an MRF electrical control
circuit electrically connected to said MRF coil which generates a
continuously decreasing output current to control the MRF coil for
continuously decelerating said valve as said valve moves from said
open to said fully closed position.
5. The fuel pump as defined in claim 1 wherein said MRF electrical
control circuit generates an increasing voltage signal to said MRF
coil as said valve moves from said open position to said closed
position.
6. The fuel pump as defined in claim 4 and comprising a spring
which urges said valve toward said closed position and wherein said
MRF electrical control circuit generates a signal to said MRF coil
when said valve is in said open position to hold said valve in said
open position against the force of said spring.
7. The fuel pump as defined in claim 6 wherein said MRF electrical
control circuit generates an increasing voltage signal to said MRF
coil as said valve moves from said open position to said closed
position.
8. A fuel pump comprising: a housing defining a pump chamber, a
fuel inlet passageway and a valve chamber fluidly connected in
series between said fuel inlet passageway and said pump chamber, a
valve having a valve head, said valve head being movably mounted in
said valve chamber and movable between an open position in which
said fuel inlet passageway is fluidly connected through said valve
chamber to said pump chamber and a fully closed position in which
said valve head blocks said fuel inlet passageway and prevents
fluid flow from said fuel inlet passageway to said pump chamber, an
actuator which, under control of a control circuit, moves said
valve head between said open and said closed position, wherein said
control circuit generates a continuously decreasing current output
signal to said actuator to continuously decelerate said valve as
said valve moves from said open to said fully closed position.
9. The fuel pump as defined in claim 8 wherein said inlet
passageway intersects said valve chamber at a location between
axial ends of said valve chamber, said valve head being axially
slidably mounted in said valve chamber, said valve head being
retracted behind said location when in said open position and
extending over and fluidly sealing said location when in said
closed position.
10. The fuel pump as defined in claim 9 wherein said actuator
comprises a solenoid.
11. The fuel pump as defined in claim 9 and comprising dampening
material disposed between an end of said valve and said
housing.
12. The fuel pump as defined in claim 8 wherein said inlet
passageway intersects said valve chamber at a location between
axial ends of said valve chamber, said valve head being rotatably
mounted in said valve chamber and including at least one axially
extending channel formed on its outer periphery, said channel
extending from said location to said pump chamber when said valve
is in said open position, said outer periphery of said valve head
extending over and fluidly sealing said location when in said
closed position.
13. The fuel pump as defined in claim 12 and comprising a motor for
rotatably driving said valve head.
14. The fuel pump as defined in claim 13 wherein said motor
comprises a stepping motor and comprising a control circuit which
controls activation of said stepping motor.
15. The fuel pump as defined in claim 8 and comprising a diaphragm
mounted in said pump chamber.
16. The fuel pump as defined in claim 15 wherein said diaphragm is
fluid permeable.
17. The fuel pump as defined in claim 8 and comprising an outlet
passageway having one end fluidly connected to said pump chamber,
said outlet passageway having a turbulence inducing layer.
Description
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates to fuel pumps and, more particularly,
to a high pressure fuel pump for use with a direct injection
internal combustion engine.
II. Description of Related Art
Direct injection internal combustion engines are enjoying increased
popularity, particularly in the automotive industry. In a direct
injection internal combustion engine, the fuel is injected directly
into the internal combustion chamber. Such direct injection engines
enjoy increased engine efficiency, fuel economy, and reduced
emissions.
Since the fuel is injected directly into the internal combustion
chamber in a direct injection engine, the fuel supply to the fuel
injectors must necessarily be provided at a high pressure. In order
to accomplish this, a high pressure fuel pump provides high
pressure fuel to fuel rails which are, in turn, fluidly connected
to the fuel injectors for the engine.
With reference first to FIG. 1, a typical prior art fuel pump 20
for a direct injection engine is shown. This fuel pump 20 includes
a housing 22 which defines an internal pump chamber 24 having an
outlet port 26. The outlet port 26 is connected to a fuel rail (not
shown) through a one-way valve 28.
Still referring to FIG. 1, the housing 22 includes a fuel inlet
passageway 30 which is fluidly connected to a source of fuel. This
fuel inlet passageway 30 is fluidly connected to the pump chamber
24 through a port 32 formed in the housing 22.
In order to pump fuel from the pump chamber 24 out through the
outlet port 26, a piston 34 has one end positioned within the pump
chamber 24 and is reciprocally driven by the camshaft of the
engine. Consequently, as the piston 34 moves into the pump chamber
24, the piston 34 pressurizes the fuel in the pump chamber 24 thus
forcing the fuel out through the outlet port 26 and to the fuel
rail assuming that the inlet port 32 is closed. Conversely, as the
piston 34 moves outwardly from the pump chamber 24, the piston 34
inducts fuel through the inlet passage 30 and inlet port 32,
assuming that it is open, and into the pump chamber 24.
A valve 36 is axially slidably mounted within the housing 22 and
this valve 36 includes an enlarged diameter valve head 38 which
overlies the inlet port 32 to the pump chamber 24. When the valve
36 is extended so that the valve head 38 is spaced apart from the
port 32, the flow of fuel from the inlet passageway 30 and to the
pump chamber 24 can occur through the inlet port 32. Conversely,
with the valve head 38 abutting against the port 32, the valve head
38 closes the inlet port 32 so that fuel is pumped out through the
outlet port 26 as the piston 34 moves into the pump chamber 24.
In order to control the movement of the valve 36 between its open
and closed position, a spring 40 urges the valve 36 towards its
closed position while a solenoid 42, when activated, holds the
valve 36 in an open position. Consequently, upon deactivation of
the solenoid 42, the spring 40 returns the valve to its closed
position thus terminating fluid flow through the inlet port 32.
In operation, the movement of the piston 34 out from the pump
chamber 24 creates a suction which moves the valve 36 to an open
position. Once open, the actuation of the solenoid 42 maintains the
valve 36 in its open position thus allowing fuel flow from the
inlet passageway 30 into the pump chamber 24. As the piston 34
begins to move back into the pump chamber 24, deactivation of the
solenoid 42 allows the spring 40 to return the valve 36 to its
closed position so that the pressurized fuel in the pump chamber 24
flows out through the outlet port 26 as desired.
While the previously known fuel pumps for direct injection engines
have proven adequate in supplying sufficient high pressure fuel to
the fuel rails for the engine, the fuel pump creates an undesirable
high level of noise for automotive uses. Most of this noise,
furthermore, is attributable to contact or impact between the valve
36 and the pump housing 22 as the valve 36 reciprocates between its
open and its closed position. This contact occurs not only between
the valve head 38 and the valve seat 39 forming the inlet port 32,
but also between an anchor 44 of the valve 36 and the pump
housing.
SUMMARY OF THE PRESENT INVENTION
The present invention provides a plurality of pump designs which
overcome the above-mentioned disadvantages of the previously known
pump designs.
The pump design of the present invention also includes a pump
housing which defines a pump chamber as well as a piston
reciprocally mounted to the housing and movable into and out from
the pump chamber. The present design also includes a valve which is
movably mounted in the housing and which establishes fluid
communication between the inlet passageway and the pump chamber as
well as blocks fluid flow from the fuel inlet passageway to the
pump chamber in synchronism with movement of the piston 34.
In a first embodiment of the invention, an electrical control
system is provided for controlling the actuation of the valve
solenoid. This control circuit generates a pulse width modulated
(PWM) signal to the solenoid. Unlike the previously known fuel pump
designs, however, the control system varies the width of the pulses
generated by the control system to decelerate the movement of the
valve just prior to its contact with the housing. Consequently, by
decelerating the valve prior to contact between the valve head and
its valve seat, as well as contact between the valve anchor and the
valve housing, pump noise is effectively reduced.
In a second embodiment of the invention, a chamber containing
magneto-rheological fluid (MRF) is disposed around a portion of the
valve while an MRF coil is disposed around the MRF chamber to
control the activation of the fluid in the MRF chamber. In this
embodiment of the invention, the MRF coil is activated just prior
to contact between the valve and the pump housing to effectively
decelerate the speed of movement of the valve just prior to impact
between the valve and the pump housing. Such deceleration, as
before, reduces the amount of noise caused by impact of the valve
against the pump housing.
In one form, a solenoid is also contained within the housing and
cooperates with the valve to hold the valve in an open position for
a short period during the pump cycle. However, alternatively, the
solenoid may be eliminated and the valve may be maintained open for
that same period during the pump cycle by activation of the MRF
coil. Such activation effectively operates to prevent movement of
the valve and thus maintain it in an open position during that
desired period of the pump cycle.
In a still further embodiment of the present invention, the valve
head is slidably mounted within a valve chamber while an inlet
passageway intersects that valve chamber at a predetermined
location. As before, the valve is movable between an open and a
closed position by operation of the spring and solenoid, but unlike
the previously known fuel pumps, the valve head does not impact
against the pump housing and thus does not create the noise of the
previously known pumps. Instead, when in its open position, the
valve head is retracted into the valve chamber by a distance
sufficient to expose the fuel inlet passageway to the valve chamber
thereby establishing fluid communication from the fuel source and
to the pump chamber. Conversely, movement of the valve to its
extended closed position causes the valve head to cover and fluidly
seal against the walls of the valve cavity thus blocking
communication between the inlet passageway and the pump
chamber.
In a still further modification of the fuel pump of the present
invention, the valve head is positioned within the valve chamber
while the inlet fuel passageway intersects the valve chamber at a
predetermined location. However, rather than reciprocally moving
the valve within the valve chamber, the valve is instead rotatably
driven by a motor so that the valve head rotates in the valve
chamber.
In order to establish fluid communication between the fuel inlet
passageway and the pump chamber, at least one, and preferably
several circumferentially spaced and axially extending channels are
formed on the outer periphery of the valve head. As each channel
rotates into registration with the inlet fuel passageway, fluid
communication is established between the inlet fuel passageway and
the pump chamber through the valve head channel. However, since the
valve head merely rotates within the valve chamber and does not
impact against the pump housing, pump noise is effectively
eliminated.
The present invention provides still further improvements to reduce
pump noise. A still further noise reduction strategy is the
provision of a turbulence surface along the outlet passage from the
pump chamber. Such a turbulence surface effectively reduces
pulsations caused throughout the fuel supply system and thus
further reduces noise from that system.
In yet a further strategy, a diaphragm is positioned within the
pump chamber. The diaphragm flexes in unison with the
pressurization of the pump chamber by the piston and also reduces
pulsations in the fuel system which otherwise would cause
noise.
BRIEF DESCRIPTION OF THE DRAWING
A better understanding of the present invention will be had upon
reference to the following detailed description when read in
conjunction with the accompanying drawing, wherein like reference
characters refer to like parts throughout the several views, and in
which:
FIG. 1 is a prior art longitudinal sectional view of a prior art
fuel pump for a direct injection internal combustion engine;
FIG. 2 is a view similar to FIG. 1, but illustrating a modification
thereof;
FIG. 3 is a fragmentary view illustrating the valve in a closed
position;
FIG. 4 is a view illustrating the output signal from the solenoid
control circuit;
FIG. 5 is a view similar to FIG. 2, but illustrating a modification
thereof;
FIG. 6 is a view similar to FIG. 5, but illustrating a modification
thereof;
FIG. 7 is a graph illustrating the activation of the MRF coil as a
function of time for the embodiment of the invention illustrated in
FIG. 6;
FIG. 8 is a flowchart illustrating the operation of the embodiment
of the invention illustrated in FIG. 6;
FIG. 9 is a view similar to FIG. 7, but illustrating the operation
of the embodiment of the invention illustrated in FIG. 5;
FIG. 10 is a view similar to FIG. 2, but illustrating a
modification thereof;
FIG. 11 is a view similar to FIG. 10, but illustrating the valve in
an open position;
FIG. 12 is a view similar to FIG. 10;
FIG. 13 is a sectional view illustrating the valve head;
FIG. 14 is a longitudinal sectional view illustrating yet a further
modification of the present invention;
FIGS. 15A and 15B are diagrammatic views illustrating yet a further
modification of the present invention; and
FIG. 16 is a flowchart illustrating the operation of the embodiment
of the invention illustrated in FIG. 2.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE PRESENT
INVENTION
With reference first to FIG. 2, a first embodiment of a high
pressure fuel pump 20 is shown which is substantially identical to
the previously described prior art fuel pump of FIG. 1 so that the
reference characters of FIG. 1 also apply to FIG. 2. As such, the
fuel pump 20 includes a pump housing 22 defining a pump chamber 24
having an outlet port 26. A one-way valve 28 is provided at the
outlet port 26 which is connected to a fuel rail (not shown) for a
direct injection engine.
The housing also includes a fuel inlet passageway 30 which fluidly
communicates with the pump chamber 24 through the fluid port 32. A
piston 34 is then reciprocally driven into the pump chamber 24 to
pressurize the fuel in the pump chamber 24 and provide that
pressurized fuel to the fuel rail and then, as the piston 34 moves
out of the pump chamber 24, open the valve 36 and induct fuel from
the inlet passageway 30, through the port 32, and into the pump
chamber 24.
The elongated valve 36 is reciprocally movably mounted in the
housing 22 and movable between an open position, illustrated in
FIG. 2, and a closed position, illustrated in FIG. 3. In its open
position, the valve head 38 is positioned away from the portion of
the housing 22 forming its valve seat 39 around the port 32 thus
permitting fluid flow from the inlet passageway 30 and to the pump
chamber 24. Conversely, in its closed position, the valve head 38
abuts against its valve seat 39 and blocks fluid flow from the
inlet passageway 30 to the pump chamber 24.
In order to control the movement of the valve 36, a compression
spring 40 is disposed around the valve 36 and urges the valve 36
towards its closed position. However, a solenoid 42, when
activated, maintains the valve 36 in its open position (FIG.
2).
Unlike the previously known fuel pumps, however, the fuel pump 20
of the present invention includes an electrical control circuit 50
which controls the voltage, and thus the current, to the solenoid
42. As best shown in FIG. 4, the electrical control circuit 50
generates a pulse width modulated (PWM) signal 52 on its output 54
(FIG. 2) to decelerate the movement of the valve 36 as it moves
from its open and to its closed position.
In particular, as shown in FIG. 4, the pulse width modulated signal
52 decreases the pulse duration from the open position 56 of the
valve 36 and to its closed position 58 (FIG. 3) in which the valve
head 38 blocks fluid flow from the fuel inlet passageway 30 to the
pump chamber 24. This decrease in pulse width duration likewise
generates a current profile 60 (FIG. 4) for the solenoid 42 which
effectively decelerates the closure of the valve and reduces the
speed of impact of the valve head 38 against its valve seat 39.
This, in turn, reduces the noise from the fuel pump 20 caused by
the impact of the valve head 38 and the valve seat 39.
Similarly, the electrical control circuit 50 may also be used to
control the speed of impact of the valve anchor 44 against the pump
housing 22. This also is achieved by varying the pulse width
duration on the output 54 from the control circuit 50.
With reference now to FIG. 16, a flowchart is illustrated for the
control of the solenoid between the valve open time 56 and valve
closed time 58 (FIG. 4). After the algorithm is initiated at step
180, step 180 proceeds to step 182 which determines if time 56,
i.e. the initiation of the pulse train to the solenoid, has been
reached. If so, step 182 proceeds to step 184 and initiates
activation of the solenoid. Step 184 then proceeds to step 186.
At step 186 it is determined whether or not the turn-off time,
namely time 58, has been reached. If so, step 186 proceeds to step
188 and turns off the power to the solenoid. Otherwise, step 186
proceeds to step 190.
At step 190, the pulse width duty cycle is decreased in accordance
with a schedule stored in memory 192. Step 190 then proceeds back
to step 182 where the above process is reiteratively repeated until
the turn-off time 58 has been reached.
With reference now to FIG. 5, a still further modification of the
present invention is shown in which a chamber 70 filled with
magneto-rheological fluid (MRF) is provided around a portion of the
valve 36. An MRF coil 72 is then contained in the housing
surrounding the MRF chamber 70. In the well-known fashion, the
viscosity of the fluid in the MRF chamber 70 varies as a function
of the magnetic field applied to the chamber 70 by the MRF coil
72.
Consequently, in operation, an MRF control circuit 74 generates a
signal on its output 76 to control the magnitude of the magnetic
field created by the MRF coil 72.
A flowchart illustrating the operation of the invention is shown in
FIG. 8. The operation of the MRF control circuit 74 begins at step
90 and then proceeds to step 92 which determines whether or not the
fuel pump 20 is in operation. If not, step 92 branches to step 94
and terminates. However, assuming that the pump 20 is in operation,
step 92 instead branches to step 96.
At step 96, the circuit 74 determines the position of the valve 36
and then proceeds to step 98 and determines if the valve 36 is
returning to a closed position. If not, step 98 branches back to
step 96.
Otherwise, step 98 proceeds to step 100 where the MRF control
circuit 74 energizes the MRF coil 72 to decelerate the valve 36
prior to its contact with the pump housing. Step 100 then proceeds
back to step 92 where the above process is repeated.
An exemplary output from the MRF control circuit 74 is illustrated
in FIG. 9. At time 102 when the valve 36 begins to return to its
closed position (see step 98 in FIG. 8), the voltage to the MRF
coil 72 increases in a ramp or other function to time 104, i.e. the
closure of the valve 36. Consequently, the MRF fluid in the MRF
chamber 70 effectively and rapidly decreases the speed of movement
of the valve 36 just prior to contact between the valve 36 and
housing 22.
Consequently, by synchronizing the output from the MRF control
circuit 74 with the desired movement of the valve 36, the MRF fluid
in the MRF chamber 70 may be activated just prior to impact of the
valve head 38 or valve anchor 44 with the pump housing 22 to
decelerate the movement of the valve 36 and reduce the speed of the
impact. In doing so, reduction of the impact speed simultaneously
reduces the noise caused by that impact and thus reduces the noise
from the pump 20.
With reference now to FIG. 6, a still further modification of the
present invention is shown which is substantially identical to that
shown in FIG. 5, except that the solenoid 42 has been eliminated.
As previously described, the solenoid 42 (FIG. 5) is used to
maintain the valve in an open position as the piston 34 inducts
fuel from the fuel inlet passageway 30 into the pump chamber 24.
However, by proper programming of the MRF control circuit 74, the
MRF fluid in the MRF chamber 70 may be employed to maintain the
valve 36 in its open position in synchronism with the movement of
the piston 34 and without the need for the solenoid 42 (FIG.
5).
With reference now to FIG. 7, an exemplary output from the MRF
control circuit is shown. When the valve 36 is in an open position,
the MRF control circuit 74 generates a pulse 80 which increases the
viscosity of the MRF fluid in the MRF chamber 70 thus holding the
valve 36 in an open position as desired. Once the pulse 80 is
terminated at time t2, the viscosity of the MRF fluid is reduced
thus allowing the spring to return the valve 36 towards its closed
position.
However, at time t3 and thus prior to contact of the valve head 38
with its valve seat 39 on the pomp housing 22, the MRF coil is
again activated with an increasing energy thus effectively
increasing the viscosity of the MRF fluid and decelerating the
movement of the valve 36 just prior to closure of the valve 36 at
time t4 and thus just prior to the impact of the valve 36 against
the housing 22.
With reference to FIG. 10, a still further modification of the
present invention is shown in which a valve 110 is reciprocally
mounted within the housing 22 and includes a valve head 112 which
is reciprocally mounted within a valve chamber 114 formed in the
housing 22. Preferably, both the valve head 112 and the valve
chamber 114 are cylindrical in shape and the diameter of the valve
head 112 is substantially the same or slightly less than the
diameter of the valve chamber 114 so that the outer periphery of
the valve head 112 sealingly engages the inner periphery of the
valve chamber 114.
A portion of a fuel inlet passageway 116 intersects the valve
chamber 114 at a predetermined location spaced from an end 118 of
the valve chamber 114. The end 118 of the valve chamber, in turn,
is open to the pump chamber 24.
With reference now to FIGS. 10 and 11, the valve 110 is movable
between a closed position, illustrated in FIG. 10, and an open
position, illustrated in FIG. 11. In its closed position (FIG. 10)
the valve head 112 covers and sealingly closes the inlet passageway
116 thus blocking fluid flow from the inlet passageway 116 and into
the pump chamber 24. Conversely, in its open position, the valve
head 112 uncovers the location of the intersection between the
inlet passageway 116 and the valve chamber 114 and permits fluid
flow from the inlet passageway 116 into the pump chamber 24.
As before, a compression spring 120 urges the valve 110 toward an
open position while, when activated, the solenoid 122 maintains the
valve in its closed position.
Unlike the previously known fuel pump designs for direct injection
engines, the fuel pump design illustrated in FIGS. 10 and 11
completely eliminates the impact between the valve head and the
pump housing as the valve 110 moves between its open and its closed
position. Instead, the valve head 112 merely slides in the valve
chamber 114 without creating an impact with the valve housing 22. A
damping material 124 may also be provided at one end of the valve
110 to prevent impact between the valve head 112 and an inner end
of the valve chamber 114. Elimination of the impact between the
valve and the pump housing reduces pump noise in the desired
fashion.
With reference now to FIGS. 12 and 13, a still further modification
of the present invention is illustrated in which the valve 130
includes a generally cylindrical valve head 132. This valve head
132 is mounted within a likewise cylindrical valve chamber 134. The
outer diameter of the valve head 132 is substantially the same or
slightly less than the diameter of the valve chamber 134 so that
the outer periphery of the valve head 132 sealingly engages the
inner periphery of the valve chamber 134.
A part of an inlet fuel passageway 116 is also provided through the
pump housing 22 so that the passageway 116 intersects the valve
chamber 134 at a location spaced from the end 136 of the valve
chamber 134. This end 136, furthermore, is open to the pump chamber
24.
In order to selectively fluidly connect the fuel inlet passageway
116 with the pump chamber 24 in synchronism with the reciprocation
of the piston 34, at least one, and preferably several
circumferentially spaced and axially extending channels 138 are
formed along the outer periphery of the valve head 132. These
channels 138 extend from the free end of the valve head 132 to at
least the location of the inlet passageway 116. Consequently, upon
rotation of the valve head 132, as each channel 138 registers with
the inlet passageway 116, fluid communication is established
between the inlet passageway 116 and the pump chamber 124.
Conversely, the outer periphery of the valve head 132 sealingly
engages the inner periphery of the valve chamber 134 thus
preventing fluid flow from the inlet passageway 116 and to the pump
chamber 24 when the channel 138 does not register with the inlet
passageway 116.
Unlike the previously described embodiments of the invention, in
this modification of the invention, the valve 130 is rotatably
driven by a motor 140, such as a stepping motor or a DC
controllable motor, such that rotation of the valve 130 is
synchronized with the movement of the piston 34. However, the valve
130 is constrained against axial movement.
Since the valve 130 merely rotates within the pump housing 22, all
impact of the valve with the pump housing 22 is eliminated along
with noise created by such impact.
With reference now to FIG. 14, a still further strategy to reduce
noise in the fuel system for a direct injection internal combustion
engine is illustrated. In particular, an outlet pipe 150 is
attached to the outlet 28 from the pump chamber. This outlet pipe
150 includes a turbulent boundary layer 152 which enables laminar
flow to flow smoothly through the fuel system while the eddy of the
turbulent flow is trapped along the turbulent boundary layer 152.
Any conventional means, such as grooves, dimples, etc., may be used
to form the turbulent boundary layer 152.
By increasing the laminar fuel flow through the outlet pipe 150,
pressure pulsation throughout the remainder of the fuel system is
reduced thus reducing noise created by such fuel pressure
pulsation.
With reference now to FIGS. 15A and 15B, a still further
modification of the present invention is shown in which a pressure
relief chamber 170 is formed along one side of the pump chamber 24.
The pressure relief chamber 170 is covered by a diaphragm 172 which
may be fluid permeable.
In operation, as the piston 34 compresses the fuel in the pump
chamber 24 and forces that fuel out through the outlet 28, the
diaphragm flexes from the position shown in FIG. 15A to the
position shown in FIG. 15B thereby absorbing at least a portion of
the pressure pulsation caused by the piston 34. This, in turn,
reduces the amount of pressure pulsation transmitted through the
remainder of the fuel system thereby reducing noise from the fuel
pump.
From the foregoing, it can be seen that the present invention
provides a number of different strategies to reduce the noise from
the fuel pump in a high pressure fuel pump of the type used for
direct injection internal combustion engines. Having described our
invention, however, many modifications thereto will become apparent
to those skilled in the art to which it pertains without deviation
from the spirit of the invention as defined by the scope of the
appended claims.
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